Developing apparatus, developing method and storage medium

ABSTRACT

A developing apparatus includes: a substrate holder that hold a substrate horizontally; a developer nozzle that supplies a developer onto the substrate to form a liquid puddle; a turning flow generation mechanism including a rotary member that rotates about an axis perpendicular to the substrate while the rotary member is being in contact with the liquid puddle thereby to generate a turning flow in the liquid puddle of the developer formed on the substrate; and a moving mechanism for moving the turning flow generation mechanism along a surface of the substrate. The line-width uniformity of a pattern can be improved by forming turning flows in a desired region of the substrate and stirring the developer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/450,704, filed Aug. 4, 2014, and claims the benefit under 35 USC §119(1)-(d) of Japanese Patent Application No. 2013-162611 filed on Aug.5, 2013, the entire contents of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a developing apparatus for developing asubstrate after exposure, a developing method, and a storage medium usedfor the developing apparatus.

BACKGROUND ART

In a photolithography process for manufacturing of a semiconductordevice, a developer is supplied to a substrate, on which a resist filmhas been formed and which has been exposed with a predetermined pattern,so that a resist pattern is formed on the substrate. The developingprocess is sometimes performed using a method, in which a puddle of adeveloper is formed on the entire substrate by moving a nozzle having anelongate discharge opening from one end to the other end of thesubstrate while discharging the developer from the discharge opening.Since the puddle is formed while the substrate is under a stationarystate, this developing method is referred to as “stationary developingmethod”. Japanese Patent No. 3614769 (JP 3614769 B2) describes anexample of the stationary developing method. There is another developingmethod that rotates a substrate and moves a nozzle so as to move adeveloper supplying position radially on a rotating substrate. Due tothe movement of the developer supplying position and a centrifugalforce, a liquid film of the developer is formed on the substrate and thedeveloper forming the liquid film flows. Japanese Patent No. 4893799 (JP4893799 B2) describes an example of the rotary developing method.

In the stationary developing method, the liquid puddle sometimesfluctuates due to various factors, such as gas flows in a circumstancewhere the liquid puddle is formed, and vibrations of a driving mechanismconnected to a substrate holder for holding the substrate. Due to thefluctuation, concentration of the developer near the resist film mayvary in various locations within the plane of the substrate, resultingin fluctuation in the reaction of the resist film and the developer. Asa result, CPU (Critical Dimension Uniformity) of CD (Critical Dimension)which is the line width of the pattern in one exposure region (shot)within the wafer plane may be deteriorated.

In the rotary developing method, since the developer flows and isstirred on the substrate, CDU in the exposure region can be higher thanthat in the stationary developing method. However, in the rotarydeveloping method, a developer supplied to the substrate flows on thesurface of a resist film, during which the developer reacts with theresist so that the concentration of the developer changes. That is, CDmay vary in the flowing direction of the developer. A technique capableof achieving a higher CDU is thus desired. Japanese patent laid-openpublication No. JP2012074589A discloses a technique that brings thelower end of a nozzle disposed above a central portion of a substrateinto contact with a processing liquid supplied from the nozzle androtating the substrate thereby forming a liquid film on the substrate.This technique, however, is not capable of solving the foregoingproblem.

SUMMARY OF THE INVENTION

The embodiments of the present invention intend to provide a techniquethat improves the line-width uniformity, of a resist pattern, within aplane of a substrate, when a developing process is performed to anexposed substrate.

A developing apparatus in one embodiment of the present inventionincludes a substrate holder that hold a substrate horizontally; adeveloper nozzle that supplies a developer onto the substrate to form aliquid puddle; a turning flow generation mechanism including a rotarymember that rotates about an axis perpendicular to the substrate whilethe rotary member is being in contact with the liquid puddle thereby togenerate a turning flow in the liquid puddle of the developer formed onthe substrate; and a moving mechanism that moves the turning flowgeneration mechanism along a surface of the substrate.

A developing method in another embodiment of the present inventionincludes: holding a substrate horizontally by a substrate holder;supplying a developer from a developer nozzle to the substrate therebyforming thereon a liquid puddle; generating a turning flow in the liquidpuddle to stir the liquid puddle; and moving a position where theturning flow was generated.

According to the above embodiments, turning flows can be generated todesired regions of the substrate and the developer can be stirred toimprove the developer concentration uniformity. As a result, theline-width uniformity of the resist pattern is improved in a regionwhere the turning flows are formed. Accordingly, the line-widthuniformity within the plane of the substrate can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross sectional view schematically showing adeveloping apparatus in one embodiment of the present invention;

FIG. 2 is a top plan view of the developing apparatus;

FIG. 3 is a vertical cross sectional view schematically showing adeveloper nozzle provided in the developing apparatus;

FIG. 4 is a top plan view of the nozzle;

FIG. 5 is a bottom plan view of the nozzle;

FIG. 6 is a schematic diagram of a liquid puddle below the nozzle;

FIG. 7 is a schematic diagram of the liquid puddle below the nozzle;

FIG. 8 is a plan view of the liquid puddle;

FIG. 9 illustrates a process step in a first embodiment;

FIG. 10 illustrates another process step in the first embodiment;

FIG. 11 illustrates yet another process step in the first embodiment;

FIG. 12 illustrates yet another process step in the first embodiment;

FIG. 13 illustrates yet another process step in the first embodiment;

FIG. 14 illustrates yet another process step in the first embodiment;

FIG. 15 is a time chart of the process steps of FIGS. 9 to 14;

FIG. 16 is an explanatory diagram illustrating a moving path of thedeveloper nozzle over a wafer;

FIG. 17 is a time chart for a modification of the processes;

FIG. 18 is a plan view of another developing apparatus;

FIG. 19 illustrates a process step in a second embodiment;

FIG. 20 illustrates another process step in the second embodiment;

FIG. 21 illustrates yet another process step in the second embodiment;

FIG. 22 illustrates yet another process step in the second embodiment;

FIG. 23 is a time chart of the process steps of FIGS. 19 to 23;

FIG. 24 is a time chart for a modification of the process steps;

FIG. 25 illustrates a process step in a third embodiment;

FIG. 26 illustrates another process in the third embodiment;

FIG. 27 illustrates yet another process step in the third embodiment;

FIG. 28 illustrates yet another process step in the third embodiment;

FIG. 29 is a time chart of the process steps of FIGS. 25 to 28;

FIG. 30 is a time chart for a modification of the process steps;

FIG. 31 illustrates a process step in a fourth embodiment;

FIG. 32 illustrates another process step in the fourth embodiment;

FIG. 33 illustrates yet another process step the fourth embodiment;

FIG. 34 illustrates yet another process step in the fourth embodiment;

FIG. 35 a time chart of the process steps of FIGS. 31 to 34;

FIG. 36 is a time chart for a modification of the process steps;

FIG. 37 is a side elevational view of a developer nozzle in anotherdeveloping apparatus;

FIG. 38 is a plan view of the nozzle of the another developingapparatus;

FIG. 39 illustrates a process step in a fifth embodiment;

FIG. 40 illustrates another process step in the fifth embodiment;

FIG. 41 illustrates yet another process step in the fifth embodiment;

FIG. 42 is a side elevational view of a developer nozzle in yet anotherdeveloping apparatus;

FIG. 43 illustrates a process step in a sixth embodiment;

FIG. 44 illustrates another process step in the sixth embodiment;

FIG. 45 illustrates yet another process in the sixth embodiment;

FIG. 46 a time chart of the process steps of FIGS. 43 to 45;

FIG. 47 is a time chart for a modification of the process steps;

FIG. 48 is a side elevational view of yet another developer nozzle;

FIG. 49 is a lower plan view of the developer nozzle of FIG. 48;

FIG. 50 is a side elevational view of yet another developer nozzle;

FIG. 51 is a lower plan view of the developer nozzle of FIG. 50;

FIG. 52 is a side elevational view of yet another developer nozzle;

FIG. 53 is a bottom plan view of the developer nozzle of FIG. 52;

FIG. 54 is a vertical cross sectional view schematically illustratingyet another developer nozzle;

FIG. 55 is a bottom plan view of the developer nozzle of FIG. 54;

FIG. 56 is a vertical cross sectional view schematically illustratingyet another developer nozzle:

FIG. 57 is a bottom plan view of the developer nozzle of FIG. 56:

FIG. 58 is a graph showing the result of an evaluation test;

FIG. 59 is a schematic diagram illustrating minimum nozzle diameters andnozzle paths;

FIG. 60 is a schematic diagram illustrating minimum nozzle diameters andnozzle paths; and

FIG. 61 is a schematic diagram illustrating minimum nozzle diameters andnozzle paths.

DESCRIPTION OF EMBODIMENTS

<First Embodiment>

FIGS. 1 and 2 show a developing apparatus 1 according to a firstembodiment of the present invention. A wafer W having a resist filmformed on its surface is transferred to the developing apparatus 1 andis processed therein. The resist film has been exposed with apredetermined pattern. The developing apparatus 1 includes a spin chuck11 serving as a substrate holder. The spin chuck 11 is configured toabsorb (suck) a central portion of the rear surface of the wafer W suchthat the wafer W is held horizontally. The spin chuck 11 is connected toa rotating and driving unit 13 disposed below through a rotating shaft12.

The developing apparatus 1 is provided with a cup body 2 which surroundsthe wafer W held by the spin chuck 11. The cup body 2 is composed of anouter cup 21 and an inner cup 22. An upper side of the cup body 2 isopened. An upper part of the outer cup body 21 has a rectangular shape,while a lower part thereof has a cylindrical shape. The reference number23 depicts a stepped part formed on a lower part of the outer cup 21,and 24 depicts an elevation unit connected to the stepped part 23. Theinner cup 21 has a cylindrical shape, and an upper part thereof inclinesinward. When the stepped part 23 is brought into contact with a lowerend surface of the inner cup 22 during elevation of the outer cup 21,the inner cup 22 is moved upward. When a developer is removed from thewafer W, the cup body 2 is elevated as shown by the dotted lines, so asto receive the liquid scattering from the wafer W.

A circular plate 25 is disposed below the wafer W held by the spin chuck11. A ring-shaped guide member 26 having a cross section of a chevronshape is disposed outside the circular plate 25. The guide member 26guides the developer and a cleaning liquid falling down from the wafer Wto a liquid receiving part 27 disposed outside the circular plate 25.The liquid receiving part 27 is an annular recessed part. The referencenumber 28 depicts a drain pipe, which is connected to the liquidreceiving part 27. The drain pipe 28 is connected to a drain tank (notshown). A vapor-liquid separator (not shown) is disposed on the drainpipe 28, so that vapor to be exhausted and liquid to be drained areseparated from each other. The reference number 15 depicts an elevationmechanism for moving a pin 14 upward or downward. With the aid of theupward and downward movement of the pin 14, the wafer W can betransferred between a substrate transfer mechanism (not shown) and thespin chuck 11.

The developing apparatus 1 includes a developer nozzle 31. The developernozzle 31 has a function for supplying the developer to the wafer W soas to form a liquid puddle thereon, and a function for generating aturning flow in the liquid puddle. That is, the developer nozzle 31 hasnot only a function as a nozzle but also has a function as aturning-flow generating mechanism. FIG. 3 is a longitudinal sectionalview of the developer nozzle 31. FIGS. 4 and 5 are a top plan view and abottom plan view of the developer nozzle 31, respectively. The developernozzle 31 has a columnar shape elongated in the vertical direction. Arecessed part 32 is formed in a top surface of the developer nozzle 31.In a bottom surface of the recessed part 32, a plurality of apertures 33are opened around a center axis of the developer nozzle 31. Eachaperture 33 is connected to a discharge opening 36 that is openedperpendicularly to a central part of a bottom surface 35 of thedeveloper nozzle 31.

The bottom surface 35 is circular, and is formed to be in parallel withthe wafer W placed on the spin chuck 11. The discharge opening 36 isopened in a central axis of the developer nozzle 31, i.e., in a centralportion of the bottom surface 35. A diameter d1 of the bottom surface 35is smaller than a diameter of the wafer W. The diameter of the wafer Wis, for example, 450 mm, but a wafer W having a smaller diameter may beused. When the diameter of the wafer W is larger, it can be expectedthat the aforementioned problems such as an amount of the developer tobe consumed, a liquid spattering and a throughput can be greatlyimproved. A resin is used for a material of the developer nozzle 31, forexample, in order to stir the developer by a surface tension, which willbe described below. As the resin, PFA(tetrafluoroethylene-perfluoroalkylvinylether copolymer) or PTFE(polytetrafluoroethylene) is used, for example.

A shaft 37 extends vertically upward from a bottom surface of therecessed part 32 along the central axis of the developer nozzle 31. Theupper end of the shaft 37 is connected to a rotating mechanism 38. Therotating mechanism 38 allows the developer nozzle 31 to rotate about thecentral axis. Namely, the developer nozzle 31 rotates about thedischarge opening 36. The downstream end of a developer supply pipe 39is opened to the recessed part 32, so that the developer supplied fromthe developer supply pipe 39 to the recessed part 32 is discharged ontothe wafer W from the discharge opening 36. The downstream end of thedeveloper supply pipe 39 is fixed onto the rotating mechanism 38. Thereference number 3A depicts a developer supply source, which isconnected to the upstream end of the developer supply pipe 39. Thedeveloper supply source 3A has a pump, a valve and so on, and suppliesthe developer to the developer nozzle 31 in accordance with controlsignals sent from a below-described control unit 10.

As shown in FIG. 3, when the wafer W is subjected to the developingprocess, the bottom surface 35 of the developer nozzle 31 opposed inproximity to the wafer W. At this time, the distance d2 between thesurface of the wafer W and the bottom surface 35 of the developer nozzle31 is, for example, 0.5 mm to 2 mm. Since the developer is dischargedonto the wafer W from the discharge opening 36, with the bottom surface35 is placed in proximity to the wafer W, a liquid puddle 30 thatcontacts with the bottom surface 35 is formed below the developer nozzle31.

Under the state in which the liquid puddle 30 is formed, the developernozzle 31 is rotated about the central axis by the rotating mechanism38. FIGS. 6 and 7 are side views showing the condition of the liquidpuddle 30 when the developer nozzle 31 is rotated. A surface tensionacts between the liquid puddle 30 and the bottom surface 35 of thedeveloper nozzle 31, so that the liquid puddle 30 and the bottom surface35 pull against each other. When the developer nozzle 31 is rotated, aforce urging the liquid puddle 30 to rotate is applied to the liquidpuddle 30 via the surface tension. Thus, as shown by the arrow in FIG.6, a liquid flow along the rotating direction of the developer nozzle31, i.e., a turning flow is generated. FIG. 8 shows the turning flow asviewed from above. In FIG. 8, the rotating direction of the developernozzle 31 is shown by the dotted line arrow, and the direction in whichthe developer flows in the liquid puddle 30 is shown by the solid linearrows.

As shown by the arrows in FIG. 7, since the turning flow is generated sothat the developer is stirred under the developer nozzle 31, thedeveloper concentration uniformity becomes higher. In detail, eventhough the resist and the developer react with each other on the surfaceof the wafer W so that the concentration of the developer on the surfaceof the wafer W lowers, the developer of a lower concentration drawsapart from the surface of the wafer W because the developer is stirred.Thus, a developer of a higher concentration, which has not reacted withthe resist, is supplied to the surface of the wafer W. As a result, thereaction between the developer and the resist is promoted. In addition,the developer concentration uniformity in a specific area, within theplane of the wafer W, located below the bottom surface 35 of thedeveloper nozzle 31 becomes high, and thus the reaction between theresist and the developer proceeds uniformly. That is to say, CDuniformity in the resist pattern is improved.

In the developing apparatus 1, the developer nozzle 31 is horizontallymoved as described below, in order that the liquid puddle 30 is spreadfrom the central portion to the peripheral portion of the wafer W.Simultaneously with the horizontal movement of the developer nozzle 31,the wafer W is rotated. Thus, the bottom surface 35 of the developernozzle 31 is caused to pass through the whole surface of the wafer W, sothat the developer over the whole surface of the wafer W is stirred. Thediameter d1 of the bottom surface 35 of the developer nozzle 31, therotating speed of the wafer W, the horizontal moving speed of thedeveloper nozzle 31 are set such that the bottom surface 35 of thedeveloper nozzle 31 can pass through the entire surface of the wafer W.The horizontal moving speed of the developer nozzle 31 is 10 mm/secondto 100 mm/second, for example. The diameter d1 of the bottom surface 35is 50 mm to 200 mm, for example. The rotating speed of the wafer W ispreferably not more than 100 rpm and more preferably 10 rpm to 50 rpm,in order to prevent liquid spattering upon discharge of the developeronto the wafer W. In addition, in order to sufficiently stir thedeveloper, the rotating speed of the developer nozzle 31 is 50 rpm to1000 rpm, for example.

Returning to FIG. 2, the developing apparatus 1 is described. Therotating mechanism 38 is fixed on the distal end of an arm 41, while theproximal end of the arm 41 is connected to a moving mechanism 42. Thearm 41 is moved upward and downward by the moving mechanism 42. Themoving mechanism 42 is moved along a horizontally-extending guide rail43 to move the developer nozzle 31 along the radius of the wafer W heldby the spin chuck 11. The reference number 44 depicts a waiting(stand-by) area of the developer nozzle 31, which is located outside thecup body 2.

In FIGS. 1 and 2, the reference number 45 depicts a cleaning liquidnozzle, which supplies a cleaning liquid (e.g., deionized water) to thewafer W so as to clean the wafer W. In FIG. 1, the reference number 46depicts a cleaning liquid supply source, which has a pump, a valve andso on, and supplies the cleaning liquid in accordance with controlsignals from the control unit 10. In FIG. 2, the reference number 47depicts an arm for supporting the cleaning liquid nozzle 45. Thereference number 48 depicts a moving mechanism, which moves the arm 47upward and downward, and is laterally moved along a guide rail 49. Thereference number 40 depicts a waiting (stand-by) area of the cleaningliquid nozzle 45, which is located outside the cup body 2.

The developing apparatus 1 is provided with the control unit 10comprising a computer. The control unit 10 includes a program storingunit, not shown. The program storing unit stores a program as software,for example, including instructions for carrying out a developingprocess which is described below. When the program is read out by thecontrol unit 10, the control unit 10 outputs control signals to thecomponent part of the developing apparatus 1. Thus, the respectiveoperations, such as the movement of the developer nozzle 31 by themoving mechanism 42, the movement of the cleaning liquid nozzle 45 bythe moving mechanism 48, the rotation of the developer nozzle 31 by therotating mechanism 38, the supply of the developer to the developernozzle 31 by the developer supply source 3A, the supply of the cleaningliquid to the cleaning liquid nozzle 45 by the cleaning-liquid supplysource 46, the rotation of the wafer W by the spin chuck 11, the upwardand downward movement of the pin 14, are controlled, whereby the wafer Wis subjected to the developing process and the cleaning process, asdescribed below. The program is stored in the program storing unit,under a state in which the program is stored in a storage medium such asa hard disc drive, a compact disc, a magnet optical disc, or a memorycard.

The procedures of the developing process and the cleaning processperformed by using the developing apparatus 1 are explained withreference to operational views of the developing apparatus 1 shown inFIGS. 9 to 14. A time chart in FIG. 15 is also referred to as neededbasis. This time chart shows the relationship between the time (processtime) elapsed from the start of the developing process, and the rotatingspeed of the developer nozzle 31 and the rotating speed of the wafer W.The solid line graph shows the rotating speed of the developer nozzle 31and the one-dot chain line graph shows the rotating speed of the waferW, respectively. In this time chart, the period in which the developeris discharged from the developer nozzle 31, and the period in which thedeveloper nozzle 31 is moved during the discharge of the developer areshown by bars, respectively.

Firstly, a wafer W is transferred to the developing apparatus 1 by thesubstrate transfer mechanism (not shown), and is held by the spin chuck11. Then, the developer nozzle 31 is moved from the waiting area 44 to aposition above the central portion of the wafer W, and is moved downwardsuch that the bottom surface 35 comes close to the wafer W, which hasbeen described with reference to FIG. 3 (FIG. 9). Following thereto, thedeveloper is supplied from the developer nozzle 31 to the wafer W, andthe developer nozzle 31 is rotated counterclockwise in a plan view (timepoint t1 in the chart of FIG. 15). Thus, the liquid puddle 30 largerthan the bottom surface 35 is formed between the bottom surface 35 ofthe developer nozzle 31 and the wafer W, and contacts with bottomsurface 35. Then, a turning flow is generated in the liquid puddle 30,which has been described with reference to FIGS. 6 to 8, whereby thedeveloper below the bottom surface 35 is stirred (FIG. 10).

When the rotating speed of the developer nozzle 31 increases to reach apredetermined one, the developer nozzle 31 is continuously rotated atthe predetermined rotating speed. After that, the wafer W is rotatedclockwise in plan view, while a rotating speed thereof increases. Whenthe rotating speed of the wafer W reaches 10 rpm, for example, the waferW is continuously rotated at the rotating speed of 10 rpm, and thedeveloper nozzle 31 starts to move at 10 mm/second, for example, towardthe peripheral portion of the wafer W along the surface of the wafer Won the radius thereof (time point t2). Thus, the liquid puddle 30 isspread out toward the peripheral portion of the wafer W, while theliquid puddle 30 is in contact with the bottom surface 35 of thedeveloper nozzle 31 (FIG. 11). The developer nozzle 31 may be rotated inthe same rotating direction as the wafer, in which case the developerstirring effect and improved developer concentration uniformity are alsoachieved.

The rotating developer nozzle 31 moves continuously over the wafer W soas not to overtake the spreading liquid puddle 30. The reason why thedeveloper nozzle 31 should not overtake the liquid puddle 30 is that, ifthe developer nozzle 31 overtakes the liquid puddle 30, a plurality ofliquid puddles 30 are formed on the surface of the wafer W. That is, thedeveloper puddle separation occurs on the surface of the wafer W. Theindividual liquid puddles 30 will then independently spread on thesurface of the wafer W, and interfaces (surfaces) of these liquidpuddles 30 will merge together. Due to the influence of the mergingaction, the CD of the resist pattern where the merging occurred may bedifferent from that of the resist pattern in another location. That isto say, the CDU (Critical Dimension Uniformity) of the resist patternwithin the plane of the wafer may be degraded. For this reason, themoving speed of the developer nozzle 31 is set such that the developernozzle 31 does not overtake the liquid puddle 30.

Below the liquid puddle 30 that is spreading toward the peripheralportion of the wafer W, the reaction between the resist film on thesurface of the wafer W and the developer forming the liquid puddle 30proceeds. As described above, the developer of the liquid puddle 30below the developer nozzle 31 is stirred by the turning flow, wherebythe developer concentration becomes uniform. When the developer nozzle31 is moved to a position above the peripheral portion of the wafer W sothat the whole surface of the wafer W is covered by the developer, themovement of the developer nozzle 31 is stopped (time point t3, FIG. 12).The wording “the whole surface of the wafer W” is intended to mean allthe areas in which the resist pattern is formed. For example, if a waferW has a peripheral portion not provided with the resist pattern, it isnot necessary to form a liquid puddle of the developer on such aperipheral portion of the wafer W. Although FIG. 12 shows an example inwhich the liquid puddle 30 is formed slightly inside the peripheral edgeof the wafer W, the wafer W may be coated with the liquid puddle 30 upto the peripheral edge.

As described above, until the liquid puddle 30 is formed over the wholesurface of the wafer W, the developer nozzle 31 passes through the wholesurface of the wafer W to stir the developer. FIG. 16 shows the route ofthe developer nozzle 31 a viewed from the upper surface of the wafer W.The dotted lines in FIG. 16 show a trajectory of the discharge opening36 of the developer nozzle 31. After the movement of the developernozzle 31 stops, the rotating speed of the developer nozzle 31 and therotating speed of the wafer W decrease, and then their rotation stops(time point t4). For example, simultaneously with the stopping of therotation of the developer nozzle 31, the supply of the developer fromthe developer nozzle 31 stops, and the developer nozzle 31 returns tothe waiting area 44.

After the reaction between the resist film and the developer furtherproceeds on the whole surface of the wafer W by the stationary liquidpuddle 30 existing on the wafer W (FIG. 13), the cleaning liquid nozzle45 is positioned above the central portion of the wafer W and the waferW is rotated at a predetermined rotating speed. A cleaning liquid isdischarged onto the central portion of the wafer W. Then, the cleaningliquid spreads toward the peripheral portion of the wafer W by thecentrifugal force, so that the liquid puddle 30 of the developer isremoved from the wafer W (FIG. 14). After the discharge of the cleaningliquid stops, the wafer W is continuously rotated so that the cleaningliquid is spun off from the wafer W so that the wafer W is dried.Thereafter, the wafer W is unloaded from the developing apparatus 1 bythe substrate transfer mechanism, not shown.

In the developing apparatus 1, the developer is discharged from thedeveloper nozzle 31 toward the central portion of the wafer W such thatthe liquid paddle 30 of the developer contacting with the developernozzle 31 is formed, and the turning flow is generated in the liquidpuddle 30 by rotating the developer nozzle 31. Then, while the rotationof the developer nozzle 31 and the discharge of the developer arecontinued, the liquid puddle 30 of the developer spreads over the wholesurface of the wafer W by moving the developer nozzle 31 toward theperipheral portion of the wafer W and by rotating the wafer W. After thedeveloper nozzle 31 is moved to the position above the peripheralportion of the wafer W, the supply of the developer is stopped, wherebyan amount of the developer falling down to the outside of the wafer Wcan be reduced. Thus, the consumption of the developer can be reduced.In addition, since the spreading of the developer is not dependent onthe centrifugal force, the rotating speed of the wafer W may be lowered.Thus, spattering of the discharged developer on the wafer W due torotation of the wafer W can be suppressed, and it is thus possible toavoid contamination of the wafer W by particles originated from theliquid spatters. In addition, since the developer below the developernozzle 31 is stirred by the rotation of the developer nozzle 31, theunreacted resist and the unreacted developer are readily brought intocontact with each other to promote the reaction therebetween, whichimproves the throughput.

In the stationary developing method which has been described in the“Background Art” section, after the formation of the puddle of thedeveloper on the wafer W, there is a possibility that each portion ofthe puddle might fluctuate because of an environmental factor. In thiscase, the CD varies in the plane of the wafer W. In the rotarydeveloping method, since the developer is stirred on the surface of thewafer W by the rotation of the wafer W, the CD variation caused by thefluctuation can be reduced. However, in the rotary developing method,the developer is supplied along the radial direction of the wafer W, thedeveloper flows to a position distant from the position at which thedeveloper has been supplied to the wafer W, and the flowing developercomes into contact with the resist so that the developer concentrationvaries. Thus, the CD may vary in the liquid flow direction of thedeveloper. However, with the developing apparatus 1, the turning flow isgenerated locally below the developer nozzle 31 to stir the developer,and the rotation of the wafer W and the movement of the developer nozzle31 are carried out such that the developer nozzle 31 passes through thewhole surface of the wafer W. Thus, unlike the rotary developing method,the reaction between the resist and the developer can occur highlyuniformly within the plane of the wafer W, without any variation indeveloper concentration within the plane of the wafer W due to theliquid flow of the developer. That is to say, according to thedeveloping method employing the developing apparatus 1, the CDuniformity (CDU) within the plane of the wafer W is improved as comparedwith the stationary developing method and the rotary developing method.

It is supposed that a resist film whose contact angle against water isrelatively high is formed on a wafer W, and the resist is exposed byimmersion exposure. This means that the resist having unexposed portionswhose contact angle remains high is subjected to the developing process.If this wafer W is developed by the stationary developing method, thedeveloping process proceeds while the contact angle of the unexposedportions remains high. Thus, when the cleaning liquid (deionized water)is supplied after the developing process, there is a possibility thatthe cleaning liquid film may be broken into pieces because of the waterrepellency of the unexposed portions.

However, with the developing apparatus 1, during the spreading of theliquid puddle 30 toward the peripheral portion of the wafer W, thedeveloper is stirred, whereby dissolved products produced by thedissolving of the resist spread toward the unexposed portions. When theunexposed portions come into contact with the dissolved products, theunexposed portions are hydrophilized. The breaking of the cleaningliquid film on the unexposed portion is thus prevented, and as a result,the defective development is prevented. In addition, since the developeris stirred, the developer “rakes” the dissolved product. It is thuspossible to avoid defective development such as opening failure of thepattern in which the dissolved products remain as a residue on theresist pattern.

In addition, in the aforementioned developing method using thedeveloping apparatus 1, the CD distribution within the plane of thewafer W can be adjusted by controlling the rotating speed of thedeveloper nozzle 31 and/or the moving speed of the developer nozzle 31at respective positions of the developer nozzle 31 above the wafer W.Since the CD distribution can be adjusted by controlling a fewparameters, only a short time is required for the adjustment of thedeveloping apparatus 1 in order to improve the CD uniformity within theplane of the wafer W.

The developing process in one modification of the first embodiment isdescribed. FIG. 17 shows a time chart for this modification, whichdiffers from the time chart of FIG. 15 in the controlling of therotating speed of the developer nozzle 31. In this modification, as thedeveloper nozzle 31 moves from the central portion of toward theperipheral portion of the wafer W, the rotating speed of the developernozzle 31 gradually increases. After the developer nozzle 31 reaches aposition above the peripheral portion, the rotating speed continues toincrease for a predetermined period of time. After that, the rotatingspeed decreases to stop the rotation of the developer nozzle 31. Exceptfor the foregoing, the operations of the respective component parts arecontrolled in the same manner as the first embodiment.

Since the liquid puddle 30 spreads from the central portion toward theperipheral portion, the time period during which a portion of the waferW is in contact with the developer becomes shorter according to theproximity to the peripheral edge of the wafer W. Thus, in thismodification, the developer nozzle 31 is controlled such that therotating speed thereof increases as it approaches the peripheralportion, so that the stirring of the developer is promoted and thereaction between the developer and the resist is thus promoted. That is,by controlling the rotating speed as described above, the CD uniformityin the plane of the wafer W can be further improved.

Although the wafer W is rotated in the first embodiment, in order tospread the liquid puddle 30 from the central portion toward theperipheral portion of the wafer W, such a rotation is not alwaysnecessary. In one modification, bottom surface 35 of the developernozzle 31 is formed to have the same or larger size than that of thewafer W, and the bottom surface 35 is positioned close to the wafer W.The discharge opening 36 of the bottom surface 35 is located above thecentral portion of the wafer W. Then, the developer is supplied from thedeveloper nozzle 31 and the developer nozzle 31 is rotated. Thedeveloper nozzle 31 is not moved laterally. Thus, while a turning flowis formed, the liquid puddle 30 is spread out from the central portiontoward the peripheral portion of the wafer W, so that the developer isstirred over the whole surface of the wafer W. When the developer nozzle31 is rotated, a turning liquid flow is generated in an area right belowthe bottom surface 35; and also in an area slightly outside the bottomsurface 35, a turning liquid flow is generated which flows along withthe turning liquid flow below the bottom surface 35. Thus, in a casewhere a turning flow is formed without rotating the wafer W and withoutlaterally moving the developer nozzle 31 as mentioned above, the size ofthe bottom surface 35 of the developer nozzle 31 may be slightly smallerthan the surface of the wafer W.

In the foregoing embodiment and the embodiments to be described later,the shape of the substrate to be processed by the developing apparatus 1is not limited to circular, but maybe rectangle, for example. In theforegoing embodiment, the liquid puddle of the developer is formed onthe wafer W. However, a process liquid which is to be supplied to thewafer W is not limited to a developer; a cleaning liquid may be suppliedto the wafer W to form a liquid puddle like the developer so as to cleanthe wafer W.

In the first embodiment described above, in place of moving thedeveloper nozzle 31 from the position above the central portion to theposition above the peripheral portion of the wafer W, the developernozzle 31 may be moved from the position above the peripheral portion tothe position above the central portion. During this movement, therotation of the developer nozzle 31, the discharge of the developer andthe rotation of the wafer W are performed, similarly to the firstembodiment. That is, the liquid puddle 30 spreads from the peripheralportion toward the central portion of the wafer W, and the turning flowis formed in the liquid puddle 30. However, note that, when the liquidpuddle 30 spreads in this manner, interfaces (surfaces) of the developerspreading over the surface of the wafer W merge at the central portionof the wafer W. As described above, there is a possibility that the CDUin the plane of the wafer W might be degraded due to the merging of thedeveloper. Thus, the liquid puddle 30 preferably spreads from thecentral portion toward the peripheral portion of the wafer W.

In the foregoing embodiment, the moving of the developer nozzle 31 alongthe radial direction of the wafer W and the rotating of the wafer W aresimultaneously performed to form the liquid puddle 30 on the wholesurface of the wafer W. However, the method of forming the liquid puddle30 is not limited thereto. In one modification, the developer issupplied to form a puddle along the radial direction of the wafer W, bymoving the developer nozzle 31 from the central portion toward theperipheral portion of the wafer W, as described above, while the wafer Wis under a stationary state. After that, the wafer W is rotated so thatthe developer flows on the surface of the wafer W by the centrifugalforce, whereby the whole wafer W is coated with the developer. Thisprocess can also reduce the developer consumption, prevent spattering ofthe developer, and promote the reaction due to the flow of thedeveloper. However, in order to improve the CDU in the plane of thewafer W, it is effective that the rotation of the wafer W and themovement of the developer nozzle 31 are simultaneously performed.

<Second Embodiment>

Next a second embodiment is described, focusing on the differences fromthe first embodiment. FIG. 18 is a plan view showing a developingapparatus 5 used in the second embodiment. The developing apparatus 5differs from the developing apparatus 1 in that the two developernozzles 31 are provided. The developer supply pipe 39, the arm 41, themoving mechanism 42, the guide rail 43 and the waiting area 44 areprovided for each of the developer nozzles 31. Thus, the rotation, thedischarge of the developer and the movement in the radial direction ofthe wafer W can be independently performed by each developer nozzle 31.For the convenience of explanation, these developer nozzles 31 are shownby the first developer nozzle 31A and the second developer nozzle 31B.

A developing process in the second embodiment is explained withreference to the operational views of the developing apparatus 5 shownin FIGS. 19 to 22 and the time chart shown in FIG. 23. Similarly to FIG.15, the time chart of FIG. 23 shows the rotating speed of the wafer W,the rotating speed of the developer nozzle, the time period at which thedeveloper is discharged and the time period at which the developernozzle is moved. The variation of the rotating speed of the firstdeveloper nozzle 31A is shown by the solid line, and the variation ofthe rotating speed of the second developer nozzle 31B is shown by thetwo-dot chain line.

Firstly, the first developer nozzle 31A is placed in a position inproximity above the central portion of the stationary wafer W, similarlyto the first embodiment (FIG. 19). Although not shown in the drawings,the second developer nozzle 31B waits above a predetermined position(hereinafter referred to as “intermediate portion”) on the diameter ofthe wafer W between the central portion and the peripheral portion ofthe wafer W. The first developer nozzle 31A is rotated counterclockwisein a plan view, and a developer is discharged from the first developernozzle 31A (time point s1 in the time chart of FIG. 23). Thus, theliquid puddle 30 is formed below the first developer nozzle 31A, and aturning flow is generated in the liquid puddle 30 (FIG. 20).

When the wafer W starts rotating clockwise in a plan view and thenreaches a predetermined rotating speed, the first developer nozzle 31Amoves toward a position above the peripheral portion of the wafer W(time point s2), so that the liquid puddle 30 is spread out to theperipheral portion of the wafer W. Thereafter, the second developernozzle 31B is lowered to come close to the intermediate portion of thewafer W, so as to be located above the liquid puddle 30 formed by thefirst developer nozzle 31A. The second developer nozzle 31B is rotatedcounterclockwise in a plan view, and the developer is discharged fromthe second developer nozzle 31B (FIG. 21, time point s3). Thus, aturning flow is also generated in the liquid puddle 30 below the seconddeveloper nozzle 31B. The second developer nozzle 31B rotates anddischarges the developer, and at the same time, the second developernozzle 31B is moved toward the peripheral portion of the wafer W alongthe radius of the wafer W in the direction opposed to the movingdirection of the first developer nozzle 31A.

The first and second developer nozzles 31A and 31B are continuouslymoved toward the peripheral portion of the wafer W. When they reachpositions above the peripheral portion so that the liquid puddle 30 isformed on the whole surface of the wafer W, the movement of thedeveloper nozzles 31A and 31B is stopped (FIG. 22, time point s4).Thereafter, the rotating speeds of the developer nozzles 31A and 31 bdecrease to stop the rotation thereof, and the discharging of thedeveloper from the developer nozzles 31A and 31B is stopped (time points5). In this manner, until the discharge of the developer is stopped,the first developer nozzle 31A passes through the whole surface of thewafer W, similarly to the developer nozzle 31 of the first embodiment.After the discharge of the developer from the respective developernozzles 31A and 31B is stopped, the reaction of the resist proceeds bythe liquid puddle 30 of the developer, similarly to the firstembodiment. After a predetermined period of time has elapsed from thetime point s5, the wafer W is rotated and a cleaning liquid is suppliedthereto, so that the developer is removed from the wafer W.

In the second embodiment, as described above, the developer on thecentral portion of the wafer W is stirred by the developer nozzle 31A,and the developer between the intermediate portion and the peripheralportion of the wafer W is stirred by the developer nozzles 31A and 31B.Namely, the second developer nozzle 31B is disposed for assisting theoperation for stirring the liquid puddle 30 by the first developernozzle 31A. Due to this process performed in this manner, the stirringof the developer is promoted in an area from the intermediate portion tothe peripheral portion, so as to improve the developer concentrationuniformity. Thus, the CD uniformity of the resist pattern in the planeof the wafer W can be more reliably improved. In particular, if the sizeof the wafer W is large, the amount of the dissolved product flowingtogether with the flow in the liquid puddle 30 toward the peripheralportion of the wafer W (described in the description of the firstembodiment) may increase, so that it may make it difficult to achievehigh developer concentration uniformity. Thus, the stirring of thedeveloper by using the respective developer nozzles 31A and 31B isadvantageous.

FIG. 24 shows a time chart in one modification of the second embodiment.The time chart of FIG. 24 differs from the time chart of FIG. 23 in thatthe rotating speed of the developer nozzle 31 is increased as thedeveloper nozzle 31 moves toward the peripheral portion of the wafer W,similarly to the modification of the first embodiment. In this example,although the rotating speeds of the first and second developer nozzles31A and 31B are both increased, only one of them may be increased.

In the foregoing embodiment, although the first developer nozzle 31A andthe second developer nozzle 31B are rotated in the same direction, theymay be rotated in opposite directions. The rotating speeds of thedeveloper nozzles 31A and 31B are 50 rpm to 1000 rpm, for example. Therotating speeds may be identical to each other or different from eachother. The bottom surface 35 of the of the second developer nozzle 31Band the bottom surface 35 of the first developer nozzle 31A may beidentical to each other in size or different from each other in size. Ina case where the sizes of the bottom surfaces 35 are different from eachother, the size of the bottom surface 35 of the second developer nozzle31B may be smaller than that of the bottom surface 35 of the firstdeveloper nozzle 31A, for the purpose of assisting the stirringoperation of the first developer nozzle 31A. In another embodiment, thesecond developer nozzle 31B may be operated such that it does notdischarge the developer but just rotates to stir the developer. In yetanother embodiment, the first developer nozzle 31A and the seconddeveloper nozzle 31B may be operated such that, after the firstdeveloper nozzle 31A forms the liquid puddle 30 at the central portionof the wafer W, supply of the developer from the first developer nozzle31A is stopped and the supply of the developer from the second developernozzle 31B is started to spread out the liquid puddle 30 to theperipheral portion of the wafer W. In this case, both of the developernozzles 31A and 31B may be rotated and move to the peripheral portion ofthe wafer W in the same manner as in the second embodiment.

<Third Embodiment>

Next, a third embodiment is described. In the third embodiment, thedeveloping apparatus 5 explained in the second embodiment is used. Adeveloping process in the third embodiment is explained with referenceto the operation diagrams of the developing apparatus 5 shown in FIGS.25 to 28. Similarly to the second embodiment, a time chart of FIG. 29shows the rotating speed of the wafer W in the developing process in thethird embodiment, the rotating speeds of the respective developernozzles, the discharge time periods of the developer and the moving timeperiods of the respective developer nozzles.

The first developer nozzle 31A is located above the central portion ofthe wafer W, and the second developer nozzle 31B is located above theperipheral portion of the wafer W, respectively, and they are lowered tocome close to the wafer W (FIG. 25). The developer is dischargedrespectively from the first developer nozzle 31A and the seconddeveloper nozzle 31B, and the developer nozzles 31A and 31B are rotatedcounterclockwise in a plan view. Thus, the liquid puddles 30 are formedbelow the respective developer nozzles 31A and 31B, and a turning flowis formed in each liquid puddle 30 (FIG. 26, time point v1 in chart ofFIG. 29). When the wafer W starts rotating clockwise in a plan view andreaches a predetermined rotating speed, the first developer nozzle 31Ais moved toward the peripheral portion side of the wafer W and thesecond developer nozzle 31B is moved toward the central portion side ofthe wafer W, in the same direction (time point v2).

The liquid puddles 30, which have been formed by the first developernozzle 31A and the second developer nozzle 31B, are spread out on thesurface of the wafer W by the movement of the respective developernozzles 31A and 31B (FIG. 27). Their interfaces (i.e., surfaces) mergewith each other, so that the whole wafer W is coated with the liquidpuddle 30. During this operation, similarly to the other embodiments,the developer is stirred by the turning flows below the developernozzles 31A and 31B. When the first developer nozzle 31A and the seconddeveloper nozzle 31B are positioned above the intermediate portions ofthe wafer W, the movement of these developer nozzles 31A and 31B isstopped (time point v3, FIG. 28). After that, the rotation of thedeveloper nozzles 31A and 31B is stopped, and the discharge of thedeveloper from the respective developer nozzles 31A and 31B is stopped(time point v4). During the period from when the rotation of thedeveloper nozzles 31A and 31B is started to when the rotation thereof isstopped, the whole surface of the wafer W passes through at least one ofan area right below the first developer nozzle 31A and an area rightbelow the second developer nozzle 31B. Thus, the developer is stirredover the whole surface of the wafer W.

According to the third embodiment, the first developer nozzle 31A andthe second developer nozzle 31B form the liquid puddles 30simultaneously in the different areas within the plane of the wafer W.Then, the first and second developer nozzles 31A and 31B spread theliquid puddles 30 and generate turning flows in the respective liquidpuddles 30. Thus, the liquid puddle 30 can be formed rapidly over theentire surface of the wafer W, and the developer can be stirred over theentire surface of the wafer W. As a result, the time required for thedeveloping process can be further reduced. However, if the interfaces ofthe developer puddles merge with each other on the wafer W as describedabove, there is a possibility that the CDU might be degraded. Thus, inview of the improvement of the CDU, it is preferable to perform thedeveloping process according to the first and second embodiments.

FIG. 30 shows a time chart in one modification of the third embodiment.The time chart of FIG. 30 differs from the time chart of FIG. 29 in thatthe rotating speed of the first developer nozzle 31A is increased as thefirst developer nozzle 31A is moved from a position above the centralportion of the wafer W to a position above the intermediate portion ofthe wafer W, and that the rotating speed of the second developer nozzle31B is increased as the second developer nozzle 31B is moved from aposition above the peripheral portion of the wafer W to a position abovethe intermediate portion of the wafer W. In the third embodiment, sincethe liquid paddle 30 spreads toward the intermediate portion, thecontact time between the developer and the resist becomes shorteraccording to the proximity to the intermediate portion. Thus, as shownin the time chart of FIG. 30, the rotating speeds of the developernozzles 31A and 31B are controlled so as to improve the CDU within theplane of the wafer W. Also in this third embodiment, the rotatingdirections and the rotating speeds of the developer nozzles 31A and 31Bmay be identical with each other or different from each other. The sizeof the bottom surfaces 35 of the respective developer nozzles 31A and31B may be different from each other.

<Fourth Embodiment>

Next, a fourth embodiment is described. In the fourth embodiment, thedeveloping apparatus 1 explained in the first embodiment is used. Adeveloping process of the fourth embodiment is explained with referenceto the step chart shown in FIGS. 31 to 34, focusing on the differencesfrom the first embodiment. A time chart for the fourth embodiment shownin FIG. 35 is also referred to as needed basis.

Similarly to the first embodiment, the developer nozzle 31 is positionedin proximity above the central portion of the wafer W, and a developeris discharged so that the liquid puddle 31 is formed. In addition, aturning flow is formed in the liquid puddle 30 by the rotation of thedeveloper nozzle 31 (FIG. 31, time point x1 in chart of FIG. 35). Thewafer W is rotated and the developer nozzle 31 is moved toward aposition above the peripheral portion of the wafer W (time point x2), sothat the liquid puddle 30 spreads toward the peripheral portion of thewafer W (FIG. 32). When the developer nozzle 31 is positioned above theperipheral portion of the wafer W so that the liquid puddle 30 spreadsover the whole surface of the wafer W, the discharge of the developerfrom the developer nozzle 31 is stopped (time point x3), and thedeveloper nozzle 31, which is continuously rotated, is moved toward theposition above the central portion of the wafer W (FIG. 33). Thus, theturning flow is continuously formed in the liquid puddle 30. When thedeveloper nozzle 31 is positioned above the central portion of the waferW (FIG. 34), the rotation of the developer nozzle 31 and the rotation ofthe wafer W are stopped (time point x4). Almost simultaneously with thestop of the rotation of the wafer W, a cleaning liquid is supplied fromthe cleaning liquid nozzle 45 to clean the wafer W.

As described above, since the developer nozzle 31 is reciprocatedbetween the position above the central portion of the wafer W and theposition above the peripheral portion of the wafer W, each portion ofthe whole surface of the wafer W passes twice through an area rightbelow the developer nozzle 31 and thus the developer on each portion isstirred. Thus, according to the fourth embodiment, the reaction betweenthe developer and the resist can be further promoted than the firstembodiment. As a result, the time period from when the rotation of thedeveloper nozzle 31 is stopped to when the cleaning liquid is dischargedby the cleaning liquid nozzle 45 can be set shorter than the firstembodiment. According to the fourth embodiment, the throughput can befurther improved than that of the first embodiment.

FIG. 36 shows a time chart of a modification of the fourth embodiment.The time chart of FIG. 36 differs from the time chart of FIG. 35 in thatthe rotating speed of the developer nozzle 31 is increased as thedeveloper nozzle 31 is moved from a position above the central portionof the wafer W to a position above the peripheral portion of the waferW, and that the rotating speed of the developer nozzle 31 is decreasedas the developer nozzle 31 is moved from a position above the peripheralportion to a position above the central portion. This operation promotesthe reaction between the developer and the resist on the peripheralportion, in view of the fact that the contact time between the developerand the resist shortens as approaching the peripheral portion of thewafer W, as explained in connection with the first embodiment.

In the fourth embodiment, after the developer nozzle 31 has been locatedabove the peripheral portion of the wafer W, the discharge of thedeveloper is stopped in order to reduce the developer consumption.However, the developer may be discharged even when the developer nozzleis being moved to the position above the central portion. In addition,the number of movements of the rotating developer nozzle 31 between theposition above the central portion of the wafer W and the position abovethe peripheral portion of the wafer W is not limited to the number inthe forgoing, but may be more. Namely, in the foregoing, after thedeveloper nozzle 31 is returned to the position above the centralportion of the wafer W, the developer nozzle 31 may be again moved tothe position above the peripheral portion of the wafer W.

Alternatively, the developer nozzle 31 may be reciprocated above thewafer W such that, after the discharge of the developer is started on aposition above the peripheral portion of the wafer W, the developernozzle 31 is moved to a position above the central portion of the waferW, and that the developer nozzle 31 is returned to the position abovethe peripheral portion of the wafer W. However, as described inconnection with the first embodiment, in order to improve the CDU, it ispreferable that the discharge of the developer is started at a positionabove the central portion of the wafer W.

<Fifth Embodiment>

Next, a fifth embodiment is explained. A developing apparatus used inthe firth embodiment has substantially the same structure as that of thedeveloping apparatus 1 used in the first embodiment, except that thedeveloping apparatus in the fifth embodiment is provided with arestricting member 51 for restricting spreading of the developer on thewafer W. FIGS. 37 and 38 show the restricting member 51. The restrictingmember 51 is disposed apart from the developer nozzle 31 in a travelingdirection of the developer nozzle 31 in which the developer nozzle 31 ismoved for spreading the liquid puddle 30. During the movement of thedeveloper nozzle 31, even when the developer forming the liquid puddle30 flows in the traveling direction under the influence of the movingdeveloper nozzle 31, the restricting member 51, which is located in thetraveling direction, restricts the flow of the developer.

The restricting member 51 has an arcuate shape in plan view, in thisexample. A surface of the restricting member 51 is formed of a materialsuch as PFA (tetrafluoroethylene perfluoroalkylvinylether copolymer) orPTFE (polytetrafluoroethylene). The reference number 52 depicts asupport part, via which the restricting member 51 is supported on therotating mechanism 38. Thus, the restricting member 51 is moved togetherwith the developer nozzle 31 by the movement of the arm 41.

The restricting member 51 is located to be slightly apart from above thesurface of the wafer W, when the liquid puddle 30 is formed by thedeveloper nozzle 31. Thus, even when the liquid puddle 30 is spread outover the surface of the wafer W to flow to a position below therestricting member 51, the liquid puddle 30 in contact with therestricting member 51 is pulled by the restricting member 51 by thesurface tension, so that the liquid puddle 30 cannot flow outside therestricting member 51.

A developing method of the fifth embodiment is explained with referenceto the operational views of the developing apparatus shown in FIGS. 39to 41. In the fifth embodiment, as described in the time chart of FIG.15 for the first embodiment, for example, the operations of therespective component parts of the developing apparatus are controlled.Namely, similarly to the first embodiment, the developer nozzle 31 isplaced in a position in proximity above the central portion of the waferW, the developer is discharged to form the liquid puddle 30, and thedeveloper nozzle 31 is rotated. Thus, a turning flow is formed in theliquid puddle 30 (FIG. 39).

Excessive spreading of the liquid puddle 30 in the plane of the wafer Win the traveling direction of the developer nozzle 31 is inhibited bymeans of the restricting member 51. Under this state, the liquid puddle30 is spread out toward the peripheral portion of the wafer W by themovement of the developer nozzle 31 (FIG. 40). When the developer nozzle31 is moved to the position above the peripheral portion of the wafer Wso that the liquid puddle 30 is spread over the whole surface of thewafer W, the rotation of the developer nozzle 31 and the rotation of thewafer W are stopped (FIG. 41).

Due to the provision of the restricting member 51, the developer formingthe liquid puddle 30 can be prevented from falling down to the outsideof the wafer W. Thus, the developer consumption is further reduced. Inthe fifth embodiment, similarly to the modification of the firstembodiment shown in FIG. 17, the rotating speed of the developer nozzle31 may be increased as the developer nozzle 31 is moved toward theperipheral portion of the wafer W. The shape of the restricting member51 is not limited to the arcuate shape, as long as the restrictingmember 51 can restrict the flow of the developer to the outside of thewafer W. For example, the restricting member 51 may be formed in alinear shape in a plan view.

In addition, the restricting member 51 may be operated such that it doesnot move together with the developer nozzle 31. For example, therestricting member 51 is connected to a moving mechanism that isseparated from the moving mechanism 42 of the developer nozzle 31. Theapparatus may be constituted such that, when the wafer W is processed,the restricting member 51 is moved from the outside of the wafer W to aposition above the peripheral portion of the wafer W, and is heldstationary in the position above the peripheral portion.

<Sixth Embodiment>

Next, a sixth embodiment is described. In the sixth embodiment, a liquidpuddle of a developer is firstly formed over the surface of the wafer Wwith the stationary development method described in the Background Artsection. Then, the developer in the liquid puddle 30 is stirred with themethod substantially identical to the method of the first embodiment.The developing apparatus 9 used in the sixth embodiment will bedescribed with reference to the plan view of FIG. 42, focusing on thedifference from the developing apparatus 1. The developing apparatus 9has a developer nozzle 91. The developer nozzle 91 is formed in anelongate shape and has a discharge port 92 which longer than thediameter of the wafer W. In the drawing, reference numeral 93 depicts anarm for supporting the developer nozzle 91. Reference numeral 94 depictsa moving mechanism connected to the arm 93 and moving horizontally alonga guide rail 95. Reference numeral 96 depicts a stand-by region of thedeveloper nozzle 91.

In the developing apparatus 9, a rotary member 97 is provided instead ofthe developer nozzle 31. The rotary member 97 has the same structure asthat of the developer nozzle 31, except that the discharge port 36 isnot formed in the lower surface 35 and the developer supply pipe 39 isnot connected. That is, unlike the developer nozzle 31, the rotarymember 97 does not discharge the developer; but like the developernozzle 31, the rotary member 97 stirs the developer.

The development processing of the sixth embodiment will now be describedwith reference to the operation views of the developing apparatus inFIG. 43 to FIG. 45. FIG. 46 is a time chart for the sixth embodiment.Unlike the time chart for each of the foregoing embodiments, this timechart shows the rotating speed of the rotary member 97 by a solid line.Discharge of the developer from the developer nozzle 91 is started first(time point y1 in the chart) and the developer nozzle 91 moves from oneend to the other end of a wafer W in a stationary state. The rotarymember 97 stands by at a position above a central portion of the waferW.

When the developer nozzle 91 is located at a position on the other endand the entire surface of the wafer W is coated with the liquid puddle30 of the developer, the rotary member 97 descends and the lower surface35 of the rotary member 97 approaches the central portion of the surfaceof the wafer W. Discharge of the developer from the developer nozzle 91stops. Concurrently with the stop of the discharge, the rotary member 97starts rotating counterclockwise in a plan view and the wafer W startsrotating clockwise in a plan view (time point y2). A turning flow isformed in the central part of the wafer W due to the rotation of therotary member 97 and the developer is stirred in the same manner as thatin the foregoing embodiments employing the developer nozzle 31. Forexample, simultaneously with the start of rotation, the rotary member 97starts moving along the surface of the wafer W to the peripheral portionof the wafer W.

As a result of the movement of the rotary member 97, the region in whichthe turning flow is formed in the liquid puddle 30 moves toward theperipheral portion of the wafer W. Then, rotations of the wafer W andthe rotary member 97 stop and the movement of the rotary member 97 stopsat a position above the peripheral portion of the wafer W (time pointy3). Before the stop of rotation of the rotary member 97, the lowersurface 35 of the rotary member 97 passes the entire surface of thewafer W and the developer is stirred over the entire surface of thewafer W, in the same manner as in the first embodiment. After lapse of apredetermined period from the stop of the rotation of the rotary member97, a cleaning liquid is supplied to the wafer W to remove the developerin the same manner as in the first embodiment. Even though the developeris stirred after forming the liquid puddle of the developer over thewafer W as in this sixth embodiment, the developer concentrationuniformity in a stirred region becomes higher. Accordingly, the CDUwithin the plane of the wafer W can be improved.

In the foregoing embodiment, while the rotary member 97 is moved fromthe central portion to the peripheral portion of the wafer W, the rotarymember may also be moved from the peripheral portion to the centralportion. The liquid puddle 30 may be formed also by the rotarydeveloping method. That is, a developer nozzle having a diameter of thedischarge port smaller than the diameter of the wafer W is moved tochange the discharge position of the developer between the centralportion and the peripheral portion of the rotating wafer W, by which theliquid puddle 30 may be formed over the entire surface of the wafer W.In such a rotary developing method, in a case where the supply of thedeveloper is started from the central portion of the wafer W and theliquid puddle 30 is formed by moving the supply position to theperipheral portion of the wafer W, the contact time of the wafer W withthe developer is shorter according to the proximity to the peripheralportion. In this case, the developing apparatus 9 may also be controlledsuch that the rotating speed of the rotary member 97 becomes higheraccording to the proximity to the peripheral portion of the wafer W. TheCDU in the plane of the wafer W can be improved by controlling therotating speed in such a manner.

In the foregoing embodiment, after forming the liquid puddle 30 with thedeveloper nozzle 91, the rotary member 97 is moved along the surface ofthe wafer W, thereby stirring the developer in the same manner as thefirst embodiment. Alternatively, the rotary member 97 may be moved alongthe surface of the wafer W, thereby stirring the developer in the samemanner as the developer nozzle 31 in other embodiments. When thedeveloper is stirred in the same manner as in the second or the thirdembodiments, two rotary members 97 are provided in the developingapparatus.

In the sixth embodiment, the lower surface of the rotary member 97passes the entire surface of the wafer W so as to improve the CDU in theplane of the wafer, but the developing apparatus 9 need not always becontrolled in such a way. For example, an experiment may be conducted todetermine whether CDU is lower in the central portion or in theperipheral portion of the wafer W in a case where development isperformed using the stationary developing method. Based on theexperiment result, the apparatus user may determine whether the centralportion or the peripheral portion is to be stirred. If it is determinedthat the central portion is to be stirred, the liquid puddle 30 isformed as described above and then the rotary member 97 is positionedabove the central portion and stirring is performed. In this case, itmay not be necessary to rotate the wafer W. On the other hand, if it isdetermined that the peripheral portion is to be stirred, the rotarymember 97 is positioned above the peripheral portion and the developeron the peripheral portion of the wafer W is stirred while rotating thewafer W. As described above, the developer may be stirred locally in theplane of the wafer W to improve the CDU of the wafer at thecorresponding portion. However, CDU within the plane of the wafer W canbe improved more reliably by stirring the developer over the entiresurface of the wafer W as in each of the foregoing embodiments.

<Other Configuration Examples of Nozzle>

A developer nozzle used in the each of the foregoing embodiments is notlimited to the aforementioned developer nozzle 31. Other configurationexamples of the nozzle are described. FIG. 48 shows a side surface of adeveloper nozzle 61 and FIG. 49 shows a bottom surface 35 of thedeveloper nozzle 61, respectively. The developer nozzle 61 differs fromthe developer nozzle 31 in that a lower end part of the developer nozzle61 has a larger diameter so as to form a turning flow in a wider areathan the developer nozzle 31.

Although the bottom surface 35 of the developer nozzle 61 is flat, theconfiguration thereof is not limited thereto. FIGS. 50 and 51 are a sideview and a bottom view of a developer nozzle 62. The developer nozzle 62has substantially the same configuration as that of the developer nozzle61, except that the developer nozzle 62 is provided with a projection 63on the bottom surface 35. A plurality of the projections 63 are arrangedat intervals in a circumferential direction of the bottom surface 35.Each projection 63 has an arcuate shape in a plan view extending from aperipheral portion to a central portion of the bottom surface 35. Duringrotation of the developer nozzle 62, the projections 63 form the flow ofthe developer flowing toward the central part of the bottom surface 35,whereby the stirring effect is promoted. In FIG. 51, the flow of thedeveloper is shown by the dotted arrows. Since the developer flowstoward the central part in this way, the developer is deterred frommoving to flow outward of the developer nozzle 62 during rotation of thedeveloper nozzle 62. That is, the developer discharged from thedischarge port 36 is held below the developer nozzle 62 for a relativelylong time. Accordingly, the developer can be stirred more reliably belowthe developer nozzle 62, whereby the concentration uniformity can beimproved.

In order to form the flow of the developer toward the central portion ofthe bottom surface 35, grooves may be provided instead of the projection63. FIGS. 46 and 47 show a side view and a bottom view of the developernozzle 62 provided with a plurality of grooves 64. Similarly to theprojection 63, each groove 64 has an arcuate shape extending from theperipheral part toward the central part of the bottom surface 35. Suchprojections 63 or grooves 64 may also be provided on the rotary member97.

FIG. 54 and FIG. 55 are a vertical cross sectional view and a bottomplan view of the developer nozzle 65, respectively. The developer nozzle65 has substantially the same configuration as that of the developernozzle 61, except that a number of spaced-apart discharge ports 66 areformed in a bottom surface 35, whereby the developer is supplied to thewafer W like a shower. Since the developer supplied to the developernozzle 65 is discharged from the respective discharge ports 66 onto thewafer W in a dispersed manner, the discharge pressure of the developerexerted on the wafer W can be suppressed and spattering of the developeron the wafer W can be suppressed more reliably. The spattering can alsobe suppressed by forming the lower surface 35 of the developer nozzle 65with a porous material.

A yet another configuration example of the developer nozzle isdescribed. FIG. 56 and FIG. 57 are a longitudinal cross sectional viewand a bottom plan view of a developer nozzle 71, respectively. Thereference number 72 depicts a flow-path-member rotating mechanism, whichis disposed on the arm 41 similarly to the rotating mechanism 38 of thedeveloper nozzle 31. The flow path member rotating mechanism 72 rotatesa rotating rod 73, which extends vertically downward, about a centralaxis thereof. The reference number 74 depicts a flange disposed on therotating rod 73. Holes 75 serving as developer passages are drilledthrough the flange 74 and arranged in the circumferential direction. Aspiral projection 76 serving as a flow path-forming member is formed ona lower side surface of the rotating rod 73 below the flange 74. Namely,the rotating rod 73 has a screw-like configuration.

A sleeve 77 is disposed close to the projection 76 to surround a sideperiphery of the rotating rod 73. A lower opening of the sleeve 77serves as a discharge opening 78 of the developer. Similarly to thedeveloper nozzle 61, the lower end of the sleeve 77 is diametricallyenlarged such that the developer in a wide area can be stirred by itsrotation. A bottom surface of the sleeve 77 is indicated by thereference number 79. The flange 74 is fitted into a groove 81 formed inthe sleeve 77 so as to support the sleeve 77. A belt 82 is wound aroundthe sleeve 77, so that the sleeve 77 is driven by a rotating mechanism83 disposed on the arm 41. The sleeve 77 can be rotated about a verticalaxis by driving the belt 82. The developer supply pipe 39 is disposed onthe arm 41 such that the developer is supplied from a downstream end ofthe developer supply pipe 39 to an upper opening of the sleeve 77.

Similarly to the foregoing developer nozzles, the developer nozzle 71can form the liquid puddle 30 of the developer on the surface of thewafer W, and can generate a turning flow in the liquid puddle 30. Asshown by the solid arrow in FIG. 57, the sleeve 77 and the rotating rod73 are rotated clockwise as viewed from below, with a bottom surface 79of the sleeve 77 being close to the wafer W. While the sleeve 77 and therotating rod 73 are rotated in this manner, the developer is supplied tothe upper part of the sleeve 77. As shown by the dotted arrow, thesupplied developer turns and flows downward along the projection 76 soas to form a spiral liquid flow. Owing to the rotating rod 73 which isrotating in the circumferential direction of the discharge opening 78,the liquid flow is accelerated and is discharged from the dischargeopening 78 onto the wafer W. Thus, the liquid puddle 30 in contact withthe bottom surface 79 of the sleeve 77 is formed, and a turning flow isformed in the liquid puddle 30. The turning flow is accelerated by therotation of the bottom surface 79, so that the developer is remarkablystirred below the bottom surface 79.

In the foregoing embodiment, although the sleeve 77 is rotated in orderto promote the stirring operation of the developer, the sleeve 77 neednot be rotated. In addition, the rotating rod 73 need not be rotated.That is, a turning flow can be formed in the liquid puddle 30 only byguiding the developer by the projection 76 of the rotating rod 73. Aheater, for example, may be embedded in the bottom surfaces of therespective developer nozzles. In this case, when the developer isstirred, the bottom surface may be heated by the heater to a highertemperature, so that the reaction between the developer and the resistcan be further promoted.

<Evaluation Test 1>

In order to form the liquid puddle 30 on the whole surface of the waferW in accordance with the first embodiment, there was investigated arelationship among the moving speed of the developer nozzle 31, therotating speed of the wafer W and the diameter d1 of the bottom surface35 of the developer nozzle 31, which makes it possible to form a liquidpaddle while meeting specific liquid puddle-forming conditions. Theliquid puddle-forming conditions are that the interfaces of the liquidpuddle(s) 30 merge with each other, and that the bottom surface 35 ofthe developer nozzle 31 passes through the whole surface of the wafer W(in other words, there is no portions of the surface of the wafer whichis not passed through by the trajectory of the vertical projection ofthe bottom surface 35). FIG. 58 shows a graph showing the result. Theaxis of abscissa of the graph shows the rotating speed (unit: rpm) ofthe wafer W, and the axis of ordinate thereof shows the moving speed(unit: mm/second) of the developer nozzle 31. Zone A in the graphsurrounded by the chain lines is divided into zones R1 to R11.

As shown in the right side of the graph, each of the zones R1 to R11correspond to a specific range of the diameter d1 (unit: mm) of thebottom surface 35. For the diameter d1 of the bottom surface of thenozzle corresponding to a specific zone R, the liquid puddle 30 can beformed while meeting the foregoing liquid puddle-forming conditions ifthe rotating speed of the wafer W and the moving speed of the developernozzle are set to the values corresponding to the specific zone R shownin the graph.

When the moving speed of the nozzle and the rotating speed of the waferW are set as the respective predetermined values, a minimum value(minimum nozzle diameter) of the diameter d1, which makes it possible toform while meeting the foregoing liquid puddle-forming conditions, wascalculated. In FIGS. 59, 60, and 61, the minimum nozzle diameters areshown by the solid line circles, when the moving speeds of the nozzleare set as 10 mm/second, 30 mm/second and 50 mm/second, respectively,and trajectories of the center of the bottom surface 35 of the developernozzle 31 on the wafer W are shown by the dotted lines. In thesedrawings, five wafers W are shown. The rotating speeds of the wafers Ware set as 10 rpm, 20 rpm, 30 rpm, 40 rpm and 50 rpm, in this order fromabove to below. The diameter of the wafer W shown in FIGS. 59 to 61 is300 mm.

The calculated minimum nozzle diameters are shown below. If the movingspeed of the developer nozzle 31 is 10 mm/second and the rotating speedof the wafer W is 10 rpm, 20, rpm, 30 rpm, 40 rpm or 50 rpm, the minimumnozzle diameter is 60 mm, 30 mm 20 mm, 15 mm or 12 mm. If the movingspeed of the developer nozzle 31 is 30 mm/second and the rotating speedof the wafer W is 10 rpm, 20 rpm, 30 rpm, 40 rpm or 50 rpm, the minimumnozzle diameter is 180 mm, 90 mm, 60 mm, 45 mm or 36 mm. If the movingspeed of the developer nozzle 31 is 50 mm/second and the rotating speedof the wafer W is 10 rpm, 20 rpm, 30 rpm, 40 rpm or 50 rpm, the minimumnozzle diameter is 300 mm, 150 mm, 100 mm, 75 mm or 60 mm.

Although not illustrated, the minimum nozzle diameters in the caseswhere the moving speed of the nozzle is 20 mm/second or 40 mm/secondwere also calculated. If the moving speed of the nozzle is 20 mm/secondand the rotating speed of the wafer W is 10 rpm, 20 rpm, 30 rpm, 40 rpmor 50 rpm, the minimum nozzle diameter is 120 mm, 60 mm, 40 mm 30 mm or20 mm. If the moving speed of the nozzle is 40 mm/second and therotating speed of the wafer W is 10 rpm, 20 rpm, 30 rpm, 40 rpm or 50rpm, the minimum nozzle diameter is 240 mm, 120 mm, 80 mm, 60 mm or 48mm, respectively.

The graph of FIG. 58 will be explained again. As shown in the graph, bysuitably setting the rotating speed of the wafer W, the moving speed ofthe developer nozzle 31, and the diameter of the bottom surface of thedeveloper nozzle 31, the liquid puddle 30 can be formed meeting theforegoing liquid puddle-forming conditions. Note that, as described inthe first embodiment, the rotating speed of the wafer W is preferablynot more than 50 rpm, for example.

<Evaluation Test 2>

With the use of an evaluation apparatus, a test was conducted toinvestigate whether the developer can be stirred by applying an actionfor rotating the liquid puddle. The evaluation apparatus includes acircular lower plate and a circular upper plate. The lower plate and theupper plate are opposed to each other, and the upper plate is configuredto be rotated about a center axis thereof. A liquid was supplied to aspace between the lower plate and the upper plate to form a liquidpuddle. It was examined that whether or not liquid flow was generated inthe upper portion and the lower portion of the liquid puddle, when theupper plate was rotated. In this apparatus, the space between the upperplate and the lower plate can be varied, so that a liquid thickness ofthe space is adjustable. The tests were conducted plural times, whilechanging the liquid thickness and the rotating speed of the upper plate.The contact angle of the upper surface of the lower plate against theliquid was 77.3°, and the contact angle of the lower surface of theupper plate against the liquid was 91.3°.

Table 1 below shows the result of the evaluation test 2. The flowingcondition of the liquid is shown by three degrees (∘: Good Δ: Acceptablex: Unacceptable) for the upper surface and the lower surface. From Table1, it can be understood that, when the liquid thickness is not more than1.0 mm, the liquid flows are generated in the upper surface and thelower surface of the liquid puddle. Namely, the liquid is stirred. Withthe liquid thickness being not more than 1.0 mm, particularly when therotating speed of the upper plate is set not less than 60 rpm, the goodliquid flows are generated in the upper surface and the lower surface ofthe liquid puddle. From the result of the evaluation test 2, by suitablysetting a height of the wafer W and a height of the bottom surface ofthe developer nozzle 31, it can be estimated that a turning flow can begenerated to stir the developer, as described above.

TABLE 1 Liquid 240 to Thickness 15 rpm 60 rpm 300 rpm  2.5 mm TopSurface ∘ ∘ ∘ Bottom Surface x Δ Δ 1.75 mm Top Surface ∘ ∘ ∘ BottomSurface x Δ ∘  1.0 mm Top Surface ∘ ∘ ∘ Bottom Surface Δ ∘ ∘ 0.75 mm TopSurface ∘ ∘ ∘ Bottom Surface Δ ∘ ∘

The invention claimed is:
 1. A developing method comprising: holding asubstrate horizontally by a substrate holder; supplying a developer fromat least one developer nozzle to a surface of the substrate therebyforming thereon a liquid puddle; generating a turning flow in the liquidpuddle to stir the liquid puddle; and moving a position where theturning flow is generated, wherein the generating of the turning flowand the moving of the position of the turning flow include: rotatingfirst and second rotary members in parallel to each other along thesurface of the substrate while the rotary members are being in contactwith the liquid puddle at positions different from each other, in whichthe first rotary member moves from a central part to a peripheral edgeof the substrate while generating a turning flow in the liquid puddle,and the second rotary member moves concurrently with the movement of thefirst rotary member from a position, which is closer to the peripheraledge of the substrate than the central part of the substrate, toward theperipheral edge while generating a turning flow in the liquid puddle. 2.The developing method according to claim 1, wherein the moving of theposition where the turning flow was generated is performed whilerotating the substrate holder.
 3. The developing method according toclaim 2, wherein a turning direction of the turning flow is opposite toa rotating direction of the substrate.
 4. The developing methodaccording to claim 1, wherein the turning flow is generated whilesupplying the developer from the at least one developer nozzle to thesubstrate and forming the liquid puddle of the developer.
 5. Thedeveloping method according to claim 1, wherein each of the rotarymembers has a surface portion that rotates along the surface of thesubstrate while the surface portion is opposing the substrate.
 6. Thedeveloping method according to claim 5, wherein the developer issupplied by a first developer nozzle and a second developer nozzle, andwherein the first rotary member rotates about a discharge port of thefirst developer nozzle and the second rotary member rotates about adischarge port of the second developer nozzle.
 7. The developing methodaccording to claim 1, wherein the turning flow is generated in theliquid puddle after the liquid puddle is formed over the entiresubstrate using the at least one developer nozzle.
 8. A non-transitorystorage medium for storing a computer program used in a developingapparatus for performing development processing on the substrate afterexposure, wherein the computer program executes the developing methodaccording to claim 1.